A prior-art airconditioning equipment has been so configured that electrical insulation devices are disposed on the in-room unit side and out-room unit side of each of the gas-side refrigerant pipe and liquid-side refrigerant pipe of an airconditioning equipment which is divided into an in-room unit and an out-room unit, and that the control circuit board of the in-room unit is connected with the gas-side refrigerant pipe and the liquid-side refrigerant pipe, while the control circuit board of the out-room unit is connected with the gas-side refrigerant pipe and the liquid-side refrigerant pipe, whereby the gas-side and liquid-side refrigerant pipes are used as the communication media of the control signals of the in-room unit and the out-room unit (refer to Patent Document 1).
Patent Document 1: JP-A-6-2880 (claim 1, and FIGS. 1 and 2)